About Dryopteris filix-mas (L.) Schott
Dryopteris filix-mas (L.) Schott produces semi-evergreen leaves that grow in an upright habit, reaching a maximum length of 150 cm (59 in). Each rootstock bears a single crown. Its bipinnate leaves hold 20 to 35 pinnae on each side of the rachis. Leaves taper at both ends, and the basal pinnae are roughly half the length of the middle pinnae. The pinules are relatively blunt and equally lobed all around. Leaf stalks are covered in orange-brown scales. On the abaxial surface of mature blades, five or six sori develop in two rows. When spores ripen between August and November, the indusium begins to shrivel, which releases the spores. This species hybridizes easily with Dryopteris affinis (scaly male fern) and Dryopteris oreades (mountain male fern). The rhizomes of Dryopteris filix-mas are toxic; excessive doses can cause severe poisoning, blindness, and even death. Numerous cultivars have been selected for garden cultivation, and the following have earned the Royal Horticultural Society's Award of Garden Merit: D. filix-mas 'Crispa Cristata', 'Cristata', 'Grandiceps Wills', and 'Linearis Polydactyla'.
